Medical electrical lead with deployable fixation features

ABSTRACT

A medical electrical lead adapted to be at least partially implanted in a cardiac vessel includes a fixation feature operable to change from an undeployed configuration to a deployed configuration in which the fixation feature is adapted to engage an inner surface of the cardiac vessel. A tendon is disposed within a lumen of the lead and is operatively connected to the fixation feature and adapted to cause the fixation feature to change from the undeployed configuration to the deployed configuration for acute and/or chronic fixation of the lead. In one embodiment, the fixation feature includes a deflectable region of the lead which in the deployed configuration causes a surface of the lead body to engage the inner surface of the cardiac vessel. In another embodiment, the fixation feature includes a radially expandable structure for engaging the inner surface of the vessel in the deployed configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to co-pending U.S. patent applicationSer. No. 11/422,000 entitled “MEDICAL ELECTRICAL LEAD WITH EXPANDABLEFIXATION FEATURES” and filed Jun. 2, 2009. The above-identifiedapplication is incorporated herein by reference for all purposes.

TECHNICAL FIELD

The present invention relates to devices and methods for fixation ofmedical electrical leads. Specifically, the present invention isdirected to deployable devices and methods for acute and chronicfixation of a portion of a medical electrical lead within a patient'svasculature, and in particular, the coronary vasculature.

BACKGROUND

Implantable medical devices for treating irregular contractions of theheart with electrical stimuli are known. Exemplary implantable devicesare defibrillators and pacemakers. Various types of electrical leads fordefibrillators and pacemakers have been suggested, many of which areplaced transvenously. Such leads are introduced into the patient'svasculature at a venous access site and travel through veins to thesites where the leads' electrodes will be implanted or otherwise contacttarget coronary tissue. Electrodes for transvenously-placed leads can beimplanted in the endocardium (the tissue lining the inside of the heart)of the right atrium or ventricle, or alternatively, in the branchvessels of the coronary venous system. In particular, lead electrodescan be implanted in the coronary sinus or a branch vessel thereof forsensing and/or stimulation of the left side of the heart (i.e., the leftventricle).

Various techniques have been used to facilitate fixation of theforegoing types of leads at the desired implantation sites. For leadspartially implanted within the coronary venous system, fixationtechniques should provide fixation sufficient to secure the lead in thedesired implanted position, both acutely and chronically, withoutimpeding delivery of the lead to the implantation site.

There is thus a need in the art for a device and method for fixation ofcardiac leads within the coronary vasculature which does not interferewith delivery of the lead and which can be deployed after delivery toprovide acute and/or chronic fixation.

SUMMARY

The present invention, in one embodiment, is an implantable systemcomprising a pulse generator, and a lead having a proximal end coupledto the pulse generator. The lead is configured to be partially implantedin a cardiac vessel and includes an elongate lead body defining aproximal region and a distal region, the distal region including anelectrode on the body, a deflection location on the body, and adeflectable region having a tissue-engaging outer surface. The leadfurther includes a tendon disposed at least partially within the bodyand attached to the body under tension at a first attachment locationdistal to the deflectable region. Tension in the tendon maintains thedeflectable region in a deflected shape in which the tissue-engagingouter surface can frictionally engage an inner wall of the cardiacvessel.

The present invention, in another embodiment, is a medical electricallead comprising an elongate body defining a proximal region and a distalregion. The distal region is configured to be partially implanted in acardiac vessel and includes at least one electrode on the body, andfirst and second deflectable regions. The lead further includes a firsttendon housed at least partially within and attached to the lead bodyunder tension at a first attachment location distal to the firstdeflectable region, and a second tendon housed at least partially withinand attached to the lead body under tension at a second attachmentlocation distal to the second deflectable region. Tension in the firstand second tendons maintains the first and second deflectable regions indeflected states.

The present invention, in yet another embodiment, is a method forfixation of a cardiac lead in a cardiac vessel, the lead including anelongate body defining a proximal region and a distal region, aconductor within the body, a deflectable region, and a tendon disposedwithin and operatively connected to the body at an attachment locationdistal to the deflectable region. The method comprises firsttransvenously delivering the lead such that the deflectable region islocated within the cardiac vessel in an undeployed configuration. Themethod further includes applying a tensile force to the tendon toproximally displace the tendon relative to the proximal region. Thetensile force is transmitted through the tendon to the lead body at theattachment location so as to deflect the deflectable region and cause atissue engaging surface of the deflectable region to engage a wall ofthe cardiac vessel.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a cardiac rhythm management systemincluding a pulse generator coupled to a lead deployed in a patient'sheart according to one embodiment of the present invention.

FIG. 2A is a cross-sectional view of a lead including an exemplaryfixation feature according to one embodiment of the present invention.

FIG. 2B depicts the lead of FIG. 2A with the fixation feature inundeployed and deployed configurations.

FIGS. 2C-2F are partial cross-sectional views of the distal region ofthe lead of FIGS. 2A-2B including various embodiments of the fixationfeature.

FIG. 3A is a partial cross-sectional view of a lead including adeflectable fixation feature according to another embodiment of thepresent invention.

FIG. 3B illustrates the lead of FIG. 3A with the deflectable fixationfeature in the deflected (i.e., deployed) configuration.

FIG. 3C illustrates a lead including a plurality of deflectable fixationfeatures according to another embodiment of the present invention.

FIGS. 4A and 4B illustrate a distal region of a lead within a body lumen(which as illustrated is a branch vessel of the coronary sinus)including an expandable fixation mechanism according to anotherembodiment of the present invention.

FIG. 4C is a partial cross-sectional view of the lead of FIGS. 4A-4Bshowing one exemplary structure for attaching a tendon to the fixationmechanism.

FIGS. 5A and 5B illustrate a distal region of a lead including aself-expanding fixation mechanism according to another embodiment of thepresent invention.

FIGS. 6A and 6B illustrate a distal region of a lead including anexpandable fixation mechanism according to one embodiment of the presentinvention.

FIGS. 7A-7C illustrate a distal region of a lead including an expandablefixation mechanism according to another embodiment of the presentinvention.

FIGS. 8A and 8B illustrate a distal region of a lead including aself-expanding fixation mechanism according to another embodiment of thepresent invention.

FIGS. 9A and 9B illustrate a distal region of a lead including anexpandable fixation mechanism according to another embodiment of thepresent invention.

FIGS. 10A and 10B illustrate partial cross-sectional views of analternative lead according to another embodiment of the presentinvention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 is a schematic drawing of a cardiac rhythm management system 10including a pulse generator 12 coupled to a lead 14 deployed in apatient's heart 20, which includes a right atrium 22 and a rightventricle 24, a left atrium 26 and a left ventricle 28, a coronary sinusostium 30 in the right atrium 22, a coronary sinus 31, and variouscoronary veins including a great cardiac vein 33 and other branchvessels off the coronary sinus 31 including an exemplary branch vessel34.

As shown in FIG. 1, the lead 14 includes an elongate body 35 defining aproximal region 36 and a distal region 40. The distal region 40 has adistal end portion 42 including at least one electrode 44 andterminating in a distal tip 48. In the embodiment illustrated in FIG. 1,the distal region 40 is guided through the right atrium 22, the coronarysinus ostium 30, and the coronary sinus 31, and into the branch vessel34 of the coronary sinus 31, with the distal end 42, and thus theelectrode 44 and the distal tip 48, positioned within the branch vessel34. The illustrated position of the lead 14 may be used, for example,for sensing physiologic parameters and delivering a pacing and/ordefibrillation stimulus to the left side of the heart 20. Additionally,it will be appreciated that the lead 14 may also be partially deployedin other cardiac vessels such as the great cardiac vein 33 or otherbranch vessels for providing therapy to the left side of the heart 20.

The lead 14, and other such leads according to the present invention,exemplary embodiments of which are shown and discussed in detail below,includes one or more fixation features adapted to frictionally engage aninterior surface of one or more of the cardiac vessels (e.g., thecoronary sinus 31 and the branch vessel 34) to prevent, or substantiallyimpede displacement and dislodgement of the distal end portion 42, andin particular, the electrode 44, from the branch vessel 34 (or othertarget cardiac vessel). In some embodiments, these fixation featuresadvantageously provide acute fixation without interfering with deliveryof the lead to the desired implantation position. Additionally, ifdesired, the fixation features can provide chronic fixation or,alternatively, can be adapted to permit repositioning and/or removal ofthe lead from the body when appropriate.

FIG. 2A is a cross-sectional view of a lead 50 according to oneembodiment of the present invention. As illustrated in FIG. 2A, the lead50 has an elongate lead body 54 with an outer surface 58, the body 54defining a proximal region 62 having a proximal end 66, and a distalregion 70 terminating at a distal tip 74 and including at least oneelectrode 76. The distal region 70 includes a fixation feature, which inthe illustrated embodiment includes a deflectable region 80 extendingfrom a deflection location 84 to the distal tip 74. As shown, the lead50 further includes an insulated conductor coil 85 within the lead body54. In one embodiment, the lead body 54 provides an insulating sheathfor the conductor 85. The conductor coil 85 forms an inner wall defininga lumen 88 extending from the proximal end 66 through a distal opening94 in the distal tip 74. A tendon 100 is housed within body 54, andextends from proximally beyond the proximal end 66 to an attachmentstructure 106 located at the distal tip 74. In the illustratedembodiment, the tendon 100 is disposed within the lumen 88.

In the illustrated embodiment, the attachment structure 106 is locatedoutside the distal opening 94, and operates to prevent the tendon 100from retracting proximally within the lumen 88. In other embodiments,the tendon 100 is attached to the lead 50 via an alternative attachmentstructure and at an attachment location proximal to the distal tip 74.That is, the tendon 100 can be attached to the lead 50 at any locationproviding the desired operability, as discussed below. In someembodiments, the tendon 100 may be disposed within a secondary lumenrather than the lumen 88 formed by the conductor coil 85 as illustratedin FIG. 2A.

The deflectable region 80 provides a deployable fixation feature adaptedto change between an undeflected (i.e., undeployed) configuration asshown in FIG. 2A, and a deflected (i.e., deployed) configuration. In itsdeployed configuration, the lead outer surface 58 provides a tissueengaging surface adapted to frictionally engage the inner surface of oneof the cardiac vessels (e.g., the coronary sinus 31 and the branchvessel 34) in which the lead 14 is positioned. The tendon 100 operatesto transmit a proximally directed tensile force to the lead 50 at theattachment location (i.e., in the illustrated embodiment, the distal tip74), thereby causing a shape change in the deflectable region 80. Thedeflection location 84 provides a point or localized region at which thedeflectable region 80 can preferentially deflect. In the illustratedembodiment, the attachment structure 106 prevents the tendon 100 fromretracting proximally through the lumen 88 when such a force is applied.As discussed above, the form of attachment structure 106 shown in FIG.2A is exemplary only, and in other embodiments, the tendon 100 may befixedly attached directly to the inner wall of the lumen 88. In short,any structure for attaching the tendon 100 to the lead 14 may be used.

FIG. 2B illustrates the lead 14 showing the deflectable region 80 in thedeflected (i.e., deployed) configuration. As shown in FIG. 2B, becausethe tendon 100 is fixedly attached to the lead 50 at the distal tip 74,applying a tensile force F to the tendon 100 while restraining theproximal region 62 from being proximally displaced (i.e., by graspingand holding the proximal region 62 in place while applying the tensileforce) causes the tendon 100 to move proximally relative to the proximalregion 62. This in turn causes the deflectable region 80 to deflect atthe deflection location 84. Such deflection causes the lead body outersurface 58 to contact and frictionally engage the inner wall of thecardiac vessel (e.g., the coronary sinus 31 or branch vessel 34) inwhich the deflectable region 80 is positioned. The tendon 100 may thenbe secured under tension to the lead body 54 at a proximal attachmentlocation at or near the proximal end 66 to maintain the deflectableregion 80 in the deployed configuration for fixation.

In the illustrated embodiment, the deflectable region 80 is configuredto attain a deflected shape in the form of a “J” when deployed. Theshape of the deflectable region 80 in the deployed configuration can becontrolled by various factors including, for example, the configuration,number, and spacing of deflection locations 84, attachment location ofthe tendon 100 to the lead 50, the inherent stiffness of the deflectableregion 80, and the magnitude of the proximally directed force F appliedto the tendon 100 (i.e., the amount of proximal displacement of thetendon 100 relative to the lead body 54). Thus, varying these parameterscan provide a wide range of deployed deflectable region shapes.

The operability of the deflectable region 80 can also be affected byvarying the attachment location of the tendon 100 to the lead 50. Asdiscussed above, the tendon 100 can be attached to the lead 50 at anyattachment location along the lead 50. For example, in one embodiment,the tendon 100 is attached to the lead 50 at a location proximal to thedistal tip 74 such that the distal most portions of the deflectableregion 80 remain relatively flexible. This can be desirable, forexample, because it permits the distal most portion of the lead 50 toflex with the natural motion of the heart.

FIGS. 2C-2F depict portions of the distal region 70 including thedeflectable region 80 of the lead and illustrating exemplary deflectionlocation 84 configurations according to various embodiments of thepresent invention. As shown in FIG. 2C, the lead body 54 includes arelatively stiff portion 110 and a relatively flexible portion 116located distal to the stiff portion 110. In this embodiment, thedeflection location 84 is created in the lead body 54 by a transition120 between the relatively stiff and relatively flexible portions 110,116. The relatively flexible portion 116 is pliable and willpreferentially bend with respect to the stiff portion 110 under a givenproximal force F to the tendon 100. In one embodiment, the stiff portion110 is formed by using a relatively rigid material, e.g., polyurethane,in the lead body 54, and the flexible portion 116 is formed from a morepliable material, e.g., silicone. In another embodiment, the stiffportion 110 may have a greater wall thickness than the flexible portion116. In another embodiment, the relatively stiff portion 110 may bereinforced (e.g., by a metal or fabric braid material embedded beneaththe outer surface 58) to increase its stiffness, while the relativelyflexible portion 116 may be unreinforced. Alternatively, both portions110, 116 may be reinforced with the relatively stiff portion 110 beingmore extensively reinforced than the relatively stiff portion 116.

In FIG. 2D, the deflection location 84 is formed by an electrode 122 onthe lead body 54, which locally stiffens the lead body 54 and causes themore flexible portion distal the electrode 122 to preferentially deflectupon the application of the tensile load to the tendon 100.

In FIG. 2E the deflection location 84 includes a notch 124 in the leadbody 54, which creates a localized point about which the deflectableregion 80 can deflect. FIG. 2F illustrates a similar approach in which acutout 128 is made in the lead body 54, in which a section of theinsulating sheath of the lead body 54 is removed to create thedeflection location 84.

The embodiments illustrated in FIGS. 2C-2F for creating the deflectionlocation 84 may, in some embodiments, be combined to further vary theshape of the deflectable region 80 when in the deployed configuration.For example, a lead 50 may include a deflection location 84 includingthe transition 120 between the stiff and flexible portions 110, 116, aswell as the notch 124. Additionally, in some embodiments, thedeflectable region 80 of the lead 50 may include more than onedeflection location 84 to vary the deflected shape of the deflectableregion 80. Moreover, the illustrated deflection location embodiments arein no way limiting. To the contrary, any configuration or feature whichcreates a point or zone about which the deflectable region 56 candeflect can be used.

FIG. 3A is a partial cross-sectional view of a lead 150 showing adeflectable region 160 according to another embodiment of the presentinvention. As shown in FIG. 3A, the lead 150 includes a body 162 havingan outer surface 164 and defining a proximal region 166 and a distalregion 167. The proximal region 166 includes a proximal end 168, and thedistal region includes an electrode 169 and terminates in a distal tip170. A lumen 176 extends from to the distal tip 170 and terminates in anopen distal end 180. The deflectable region 160 includes first andsecond deflection locations 186, 190. A tendon 196 is housed within thebody 162, and extends from the proximal end 168 to the distal tip 170and includes an attachment structure 200 adapted to fixedly attach thetendon 196 to the lead body 162. In the illustrated embodiment, thetendon 196 is disposed within the lumen 176, and extends through thebody 162 at apertures 204 and 206, thus defining a portion of the tendon196 extending along the outer surface 164 of the lead body 162.

As with the lead 50 described above, the deflectable region 160 providesa fixation feature adapted to change between an undeflected (i.e.,undeployed) shape as shown in FIG. 3A, and a deflected (i.e., deployed)shape in which the lead outer surface 164 provides a tissue engagingsurface adapted to frictionally engage the inner surface of one of thecardiac vessels (e.g., the coronary sinus 31 and the branch vessel 34)through which the lead 150 is delivered. The tendon 196 operates totransmit a proximally directed force applied to the tendon 196 to thedistal tip 170, thereby changing the shape of (i.e., deploying) thedeflectable region 160. The deflection locations 186, 190 are adapted tocontrol the points of deflection of the deflectable region 160. Thedeflection locations 186, 190 may be configured according to any of theembodiments described above with respect to the lead 50. It will furtherbe appreciated that any other configuration for providing points atwhich the deflectable region can deflect may be used within the scope ofthe present invention.

FIG. 3B illustrates the lead 150 with the deflectable region 160 in thedeflected (i.e., deployed) configuration. As shown in FIG. 3B, applyinga tensile force F to the tendon 196 while restraining the proximalregion 166 from being proximally displaced (i.e., by grasping andholding the proximal region 166 in place while applying the tensileforce) causes the tendon 196 to move proximally relative to the proximalregion 166. This in turn causes the deflectable region 160 to deflect atthe deflection locations 186, 190, thus changing the shape of thedeflectable region 160 as illustrated in FIG. 3B. Such deflection causesthe lead body outer surface 164 to contact and frictionally engage theinner wall of the cardiac vessel (e.g., the coronary sinus 31 or branchvessel 34) in which the deflectable region 80 is positioned. The tendon196 may then be secured under tension to the lead body 162 at or nearthe proximal end (not shown). In the illustrated embodiment, the portionof the lead 150 distal to the deflection location 190 is relativelystiff, such that it remains substantially undeflected under the actionof the tensile force F on the tendon 196. Alternatively, in otherembodiments, all or part of the portion of the lead 150 distal to thedeflection location 190 can be made relatively flexible so as to undergosome deflection under the action of this tensile force F.

Although the illustrated deflectable region 160 includes two deflectionlocations 186, 190, other embodiments may include more than twodeflection locations to create additional fixation feature shapes. Forexample, in one embodiment, three or more deflection locations areemployed to provide a sinusoidal deflected shape to the lead when in thedeployed configuration. Additionally, the deflection locations 84 and186, 190 of the leads 50 and 150, respectively, may, in someembodiments, be strategically positioned on the lead bodies so as tocontrol the direction of deflection of the respective deflectableregions. For example, in some embodiments, a plurality of deflectionlocations can be provided, each extending only partially around thecircumference of the lead, and at least some being offset from oneanother about the circumference of the lead body. In such an embodiment,each such deflection location will tend to cause the lead body todeflect in a different direction, creating a deployed configurationhaving a three-dimensional shape. It will thus be appreciated thatselectively positioning and configuring the deflection location(s) andthe deflectable region(s) can produce a wide range of shapes forfixation.

In addition, in still other embodiments, the leads 50 and/or 150 caninclude more than one tendon, each attached to the respective lead bodyat a different attachment location. In one embodiment, the lead mayinclude a first tendon attached to the lead body at a first attachmentlocation at or near the distal tip, and a second tendon attached to thelead body at a location proximal to the distal tip. For example, thelead 50 and/or 150 may be configured to have a compound shape in thedeployed configuration which is a combination of the J- and S-shapedconfigurations of FIGS. 2B and 3B. Thus, a range of shapes can beachieved, particularly when multiple tendons are used in combinationwith strategically configured deflection locations. Alternatively, thelead 50 and/or 150 can include multiple tendons, each operable todeflect a different deflectable region of the lead. In such embodiments,the physician can select the optimal deployed configurations based onthe particular patient's vascular anatomy. In multi-tendon embodiments,one or more of the plurality of tendons can be disposed within one ormore secondary lumens and not within the lumen formed by the mainconductor coil as illustrated in FIG. 3A.

FIG. 3C illustrates an exemplary multi-tendon lead 250. As shown in FIG.3C, the lead 250 is in many respects similar or identical to the leads50 and 150 described above, and includes a body 251 defining a proximalportion 252, a distal portion 254 terminating in a distal tip 255, and alumen 256 throughout. The distal portion 254 includes first and seconddeflectable regions 260, 266. A first deflection location 268 is locatedon the body 251 proximal to the first deflectable region 260, and asecond deflection location 269 is located on the body 251 between thefirst and second deflectable regions 260, 266. As further shown, thelead 250 includes a first tendon 272 housed partially within the body251 in the lumen 256 and attached to the body 251 at a first attachmentlocation 273 distal to the second deflection location 269. The lead 250further includes a second tendon 272 housed partially within the body251 in the lumen 256 and attached to the body 251 at a second attachmentlocation 275 proximate the distal tip 255.

In the embodiment illustrated in FIG. 3C, the first tendon 272 isoperable to cause deployment of the first deflectable region 260 in themanner described above. Additionally, the second tendon 274 can beoperable to cause deflection of the second deflectable region 266 and/orthe first deflectable region 260. For example, the lead 250 can beconfigured (e.g., by differentiating the relative stiffness of the firstand second deflectable regions 260, 266) such that upon the applicationof a tensile force to the second tendon 274, the second deflectableregion 266 will preferentially deflect at the second deflection location268. The lead 250 can further be configured such that the firstdeflectable region 260 can be subsequently deflected by increasing thetensile force on the second tendon 274.

The deflectable fixation features of the leads 50, 150, and 250described above also advantageously allow the physician to return theleads to their undeployed configurations (i.e., by relieving the tensileload on the respective tendons) for repositioning and/or removing thelead as desired. In addition, if desired, the deflectable regionsdescribed above permit the physician to selectively urge the leadelectrode(s) into intimate contact with the target vessel wall. Thedeflectable regions of the leads 50, 150, 250 also can facilitatedelivery of the leads by effectively permitting the physician to steerthe leads through the tortuous coronary vasculature to the desiredimplantation site.

In some embodiments, the tissue-engaging outer surfaces of the leads 50,150, 250, particularly in their respective deflectable regions, mayinclude features to enhance engagement with the inner surface of thetarget coronary vessel. Such features may include, for example, surfaceroughening, adhesive or sticky coatings, and fibrosis-promotingcoatings. Alternatively, to facilitate extraction of the lead afterlong-term implantation, the deflectable regions may include coatings(e.g., polymer coatings such as PTFE) or other features to discouragetissue ingrowth.

FIGS. 4A and 4B illustrate a portion of a distal region of a lead 300within a body lumen (which as illustrated is the branch vessel 34)including an alternative fixation feature, which as illustrated is anexpandable fixation mechanism 310 according to another embodiment of thepresent invention. As shown in FIG. 4A, the lead 300 includes a leadbody 316 having an outer surface 320. The fixation mechanism 310 isdisposed on the lead body 316 and includes a proximal anchor 326, adistal floating ring 330, and a radially expandable structure 336attached at opposite ends to the anchor 326 and the ring 330. A tendon340 is disposed within the body (e.g., within a lumen, not shown) andattached to one or more locations on the ring 330. The position of theanchor 326 on the body 316 is fixed, while the distal ring 330 is afloating member adapted to translate along the body 316. In theillustrated embodiment, the anchor 326 is a ring fixedly attached to thelead body 316. In other embodiments, the anchor 326 may have structuresother than a ring. In one embodiment, the radially expandable structure336 is fixedly attached at one end directly to the lead body 316 to formthe anchor 326.

The radially expandable structure 336 can expand from a radiallycollapsed (i.e., undeployed) configuration as shown in FIG. 4A, to aradially expanded (i.e., deployed) configuration as shown in FIG. 4B inwhich the radially expandable structure 336 extends radially beyond theouter surface 320 of the lead body 316. In the radially expandedconfiguration, the radially expandable structure 336 is adapted to fixthe lead 300 in a desired implantation location by frictionally engagingan inner surface 344 of the branch vessel 34. In the illustratedembodiment, the radially expandable structure 336 is a stent-like deviceresembling stents known in the art for use in vascular interventionprocedures. In other embodiments, the radially expandable structure 336may have other configurations such as, for example, a radiallyexpandable coil or a plurality of randomly oriented wires connectedbetween the anchor 326 and the ring 330.

In one embodiment, the radially expandable structure 336 is normally inthe radially collapsed configuration as shown in FIG. 4A for delivery ofthe lead 300, and a proximally directed tensile force is applied to thetendon 340 to pull the tendon 340, and in turn, the ring 330, proximallyrelative to the lead body 316, thereby causing the radially expandablestructure 336 to expand radially to the configuration shown in FIG. 4B.In one such embodiment, the tendon 340 may be maintained under tensionto retain the radially expandable structure 336, and thus the fixationmechanism 310, in the deployed, radially expanded configuration. In suchembodiments, the tendon 340 may be secured to the lead body 316 afterdeploying the fixation mechanism 310. The fixation mechanism 310 canfurther be returned to the radially collapsed configuration of FIG. 4Aby releasing the tension in the tendon 340, thus permitting removaland/or repositioning of the lead 300.

Alternatively, in one embodiment, the lead 300 may include a retentionstructure such as one or more deflectable stops 350 on the body 316which may be deflected downward to permit proximal movement of the ring330 for deployment of the fixation mechanism 310, but which, onceengaged, prevent subsequent distal movement of the ring 330. It isemphasized, however, that any other structures or methods for retainingthe fixation mechanism 310 in the deployed configuration of FIG. 4B maybe used.

In another embodiment, the radially expandable structure 336 isself-expanding and is retained in the radially collapsed configurationof FIG. 4A by, for example, a retention structure (not shown) preventingspontaneous proximal movement of the ring 330 but which can bedisengaged or overcome by a sufficient proximally directed force appliedto the tendon 340. Once the retention structure is thus disengaged, theradially expandable structure 336 can self-expand to the configurationof FIG. 4B. Both of the latter two embodiments advantageously allow thetension in the tendon 340 to be removed after deployment of the fixationstructure 310. Additionally, in such embodiments, the tendon 340 may bedetachable from the fixation mechanism 310, thus permitting removal ofthe tendon 340 from the lead 310 after implantation.

FIG. 4C is a partial cross-sectional view of the lead 300 and thefixation mechanism 310 showing one exemplary structure for attaching thetendon 340 to the ring 330. As shown in FIG. 4C, the tendon 340 includesdiverging segments 352 and 353 extending through apertures 356 and 357,respectively, in the lead body 316. As further shown, the tendonsegments 352, 353 extend along the lead body 316 between the radiallyexpandable structure 336 and the outer surface 320 and are attached tothe ring 330. In the illustrated embodiment, the apertures 356, 357 arelocated proximal to the anchor 326, although in other embodiments theapertures may be located between the anchor 326 and the ring 330. Insome embodiments, more than two tendon segments may be used. As isapparent from FIG. 4C, as the tendon 340 is pulled proximally relativeto the lead body 316 to deploy the fixation mechanism 310, the tendonsegments 352, 353 retract through the apertures 356, 357 and into thelead lumen. It is emphasized, however, that the tendon attachmentembodiment illustrated in FIG. 4C is exemplary only, and that anystructures or methods for operatively coupling the tendon 340 to thering 330 may be used within the scope of the invention.

In another embodiment, the fixation mechanism 310 may be configured suchthat it does not extend radially beyond the outer surface 320 of thelead body 316 when in the undeployed, radially collapsed configuration.For example, the lead 300 may, in such an embodiment, include areduced-diameter portion of the lead body 316, and the fixationmechanism 310 may reside in this reduced-diameter portion. Thisconfiguration may promote ease of delivery of the lead 300 due to thelack of fixation structures protruding beyond the lead body during suchdelivery.

FIGS. 5A and 5B illustrate a portion of a distal region of a lead 400including an alternative fixation feature, which as illustrated is aself-expanding fixation mechanism 410 according to another embodiment ofthe present invention. As shown in FIGS. 5A and 5B, the lead 400includes a body 416 on which the fixation mechanism 410 is disposed. Asfurther shown, the fixation mechanism 410 includes a proximal floatingring 426, a distal anchor 430, and a radially self-expanding structure436 attached at opposite ends to the proximal ring 426 and the anchor430. A tendon 440 is disposed within the lead body 416 (e.g., within alumen, not shown) and attached to one or more locations on the ring 426.The position of the anchor 430 on the body 416 is fixed, while the ring426 is a floating member adapted to translate along the body 416. In theillustrated embodiment, the anchor 426 is a ring fixedly attached to thelead body 416. In other embodiments, the anchor 426 may have structuresother than a ring. In one embodiment, the radially expandable structureis fixedly attached at one end directly to the lead body 416 to form theanchor 426.

In the illustrated embodiment, the tendon 440 includes individualsegments 442 and 443 extending through apertures 446, 448, respectively,in the lead body 416 and attached to the ring 426. In other embodiments,an alternative structure for attaching the tendon 440 to the ring 426may be used. The self-expanding structure 436 is substantially similarin design and function to the self-expanding embodiment of the radiallyexpandable structure 336 described above.

A tensile force applied to the tendon 440 operates to pull the ring 426in the proximal direction to retain the self-expanding structure 436 inthe radially collapsed configuration of FIG. 5A for delivery of the lead400. In one embodiment, the lead 400 may be delivered to the desiredimplantation position with the tendon 440 secured, under tension, nearthe proximal end (not shown) of the lead 400. Once the lead 400 isdelivered to the desired implantation location, the tension in thetendon 440 is released, and the self-expanding structure expands to thedeployed configuration of FIG. 5B.

The embodiment of FIGS. 5A and 5B advantageously allows the tendon 340to remain in the unloaded state (i.e., not under tension) after the leadis fixed by the fixation mechanism 410. Additionally, the fixationmechanism 410 can be returned to the radially collapsed state of FIG. 5Aif desired, for example, to reposition and/or remove the lead 400 fromthe body.

The fixation mechanisms 310, 410 may be made from a variety of materials(e.g., metals, polymers) suitable for implantable devices. By way ofexample only, suitable materials include stainless steel and a widevariety of alloys and polymers. In some embodiments, the fixationmechanisms 310, 410 are made at least partially from materials havingdesirable shape memory and superelastic properties. For theself-expanding fixation mechanisms, one exemplary material exhibitingsuitable shape memory and superelasticity is Nitinol. Other suitablematerials will be ascertained by those skilled in the art based on theforegoing.

It will be appreciated that in some embodiments, the fixation mechanism410 may be configured such that it does not extend radially beyond theouter surface 420 of the lead body 416 when in the radially collapsedconfiguration. For example, the lead 400 may, in such an embodiment,include a reduced-diameter portion of the lead body 416, and thefixation mechanism 410 may reside in this reduced-diameter portion. Thisconfiguration may promote ease of delivery of the lead 400.

FIGS. 6A and 6B illustrate a portion of a distal region of a lead 500including an alternative fixation feature, which as illustrated is aradially expandable fixation mechanism 510 according to anotherembodiment of the present invention. As shown in FIG. 6A, the lead 500includes a lead body 516 having an outer surface 520. The fixationmechanism 510 is disposed on the lead body 516 and includes a proximalanchor 526, which in the illustrated embodiment is in the form of a ringattached to the body 516, a distal floating ring 530, and a radiallyexpandable structure which in the illustrated embodiment is a bellows536 attached at opposite ends to the anchor 526 and the ring 530. Atendon 540 is disposed within the lead body (e.g., within a lumen, notshown) and attached to one or more locations on the ring 530. In theillustrated embodiment, the tendon 540 is configured and attached to thering 530 in the manner illustrated in FIG. 4C above. In otherembodiments, an alternative structure for operatively attaching thetendon 540 to the ring 530 may be used. The position of the anchor 526on the body 516 is fixed, while the ring 530 is a floating memberadapted to translate along the body 516.

The fixation mechanism 510 operates in a manner substantially similar tothe fixation mechanism 310 described above. Thus, in one embodiment, theradially expandable bellows 536 are normally in the radially collapsedconfiguration as shown in FIG. 6A for delivery of the lead 500. Once thelead 500 is positioned in the body as desired, a proximally directedtensile force is applied to the tendon 540 to pull the tendon 540, andaccordingly, the ring 530, proximally relative to the body 526, therebylongitudinally compressing the bellows 536, which radially expand to thedeployed configuration shown in FIG. 6B. When so expanded, the bellows536 can engage an inner surface of the cardiac vessel in which thefixation mechanism 510 is positioned, thus fixing the lead 500 in theimplanted position.

In one embodiment, once the fixation mechanism 510 is deployed, thetendon 540 may be maintained under tension and secured to the lead body516 to retain the bellows 536, and thus the fixation mechanism 510, inthe deployed configuration. The fixation mechanism 510 can further bereturned to the radially collapsed configuration of FIG. 6A by releasingthe tension in the tendon 540, thus permitting removal and/orrepositioning of the lead 500. Alternatively, the lead 500 may, in otherembodiments, include one or more retention structures, such as thedeflectable stops 350 of the lead 300 described above, for preventingmovement of the ring 530 in the distal direction once the fixationmechanism 510 is deployed. In other embodiments (not shown), other oradditional structures are provided for retaining the fixation mechanism510 in the deployed configuration of FIG. 6B.

In other embodiments (not shown), the bellows 536 may be configured tobe self-expanding, with the fixation mechanism 510 constrained in theradially collapsed configuration for delivery in much the same manner asthe self-expanding embodiments of the fixation mechanisms 310 and 410described above.

The bellows 536 may be made from any materials having the desiredflexibility and biocompatibility properties. Exemplary materials includepolymers such as polyurethane and polyetheretherketone (PEEK™), andmetals such as stainless steel and Nitinol.

In some embodiments (not shown), the bellows 536 may include features(e.g., perforations or other cutouts) to reduce any potential occlusiveeffect and/or to encourage tissue ingrowth for chronic fixation. Forexample, in one embodiment, the bellows 536 extends only partiallyaround the circumference of the lead 500. In one embodiment, the bellows536 are in the form of a plurality of elongated lobes disposed radiallyaround the lead body 516.

It will be appreciated that in some embodiments, the fixation mechanism510 may be configured such that it does not extend radially beyond theouter surface 520 of the lead body 516 when in the radially collapsedconfiguration. For example, the lead 500 may, in such an embodiment,include a reduced-diameter portion of the lead body 516, and thefixation mechanism 510 may reside in this reduced-diameter portion. Thisconfiguration may promote ease of delivery of the lead 500.

FIGS. 7A and 7B illustrate a portion of a distal region of a lead 600including an alternative fixation feature, which as illustrated is aradially expandable fixation mechanism 610 according to anotherembodiment of the present invention. As shown in FIGS. 7A and 7B, thelead 600 includes a lead body 616 having an outer surface 620. Thefixation mechanism 610 is disposed on the lead body 616 and includes adistal floating ring 630, and a plurality of radially expandable ribs636 attached at opposite ends to the ring 630 and to the body 616. Atendon 640 is disposed partially within the body 616 (e.g., within alumen, not shown) and attached to one or more locations on the ring 630.In the illustrated embodiment, the tendon 640 is configured and attachedto the ring 630 in substantially the manner illustrated in FIG. 4Cabove. Other embodiments (not shown) may employ alternative structuresand arrangements for attaching the tendon 640 to the ring 630. The ring630 is a floating member adapted to translate along the lead body 616.

In one embodiment, the ribs 636 are normally in the radially collapsedconfiguration as shown in FIG. 7A for delivery of the lead 600. Once thelead 600 is positioned in the body as desired, a proximally directedtensile force is applied to the tendon 640 to pull the tendon 640 andthe ring 630 proximally relative to the lead body 616, thereby causingthe central portions of the ribs 636 to expand radially to theconfiguration shown in FIG. 7B for engaging the inner surface of thecardiac vessel in which the fixation mechanism 610 is positioned, thusfixing the lead 600 in the implanted position.

In one embodiment, once the fixation mechanism 610 is deployed, thetendon 640 may be maintained under tension and secured to the lead body616 to retain the radially expandable structure 636, and thus thefixation mechanism 610, in the deployed, radially expandedconfiguration. The fixation mechanism 610 can further be returned to theradially collapsed configuration of FIG. 7A by releasing the tension inthe tendon 640, thus permitting removal and/or repositioning of the lead600. Alternatively, in other embodiments, the lead 600 may include oneor more retention structures such as one or more deflectable stops 350of the lead 300 described above, for preventing movement of the ring 630in the distal direction once the fixation mechanism 610 is deployed. Inother embodiments (not shown), other or additional structures areprovided for retaining the fixation mechanism 610 in the deployedconfiguration of FIG. 7B. It is again emphasized that the illustratedstructures and methods for retaining the fixation mechanisms in theirdeployed configurations are exemplary only.

In another embodiment, the ribs 636 are self-expanding and are retainedin the radially collapsed configuration of FIG. 7A by, for example, aretention structure (not shown) preventing spontaneous proximal movementof the ring 630 but which can be disengaged by a sufficient proximallydirected force applied to the tendon 640. Once the retention structureis disengaged, the ribs 636 can self-expand to the configuration of FIG.7B. Both of the latter two embodiments advantageously allow the tensionin the tendon 640 to be removed after deployment of the fixationstructure 610.

FIG. 7C is an end view of the lead 600 showing the ribs 636 in theradially expanded configuration for engaging the inner surface of thevessel (e.g., the branch vessel 34). It will be appreciated thatalthough the lead 600 of FIGS. 7A-7C includes two radially expandableribs 636 oriented approximately 180 degrees apart, in other embodiments,one or more than two ribs may be used. In one embodiment, the lead 600includes a single radially expandable rib 636. In another embodiment,the lead 600 includes two ribs 636 oriented approximately 90 degreesapart. In such embodiments, the ribs 636 may be sized and oriented so asto bias the lead electrode into the target tissue (e.g., themyocardium). Other variations in the number and orientation of the ribs636 will be apparent to those skilled in the art based on the foregoing.

FIGS. 8A and 8B illustrate a portion of a distal region of a lead 700including an alternative fixation feature, which as illustrated is aself-expanding fixation mechanism 710 according to another embodiment ofthe present invention. As shown in FIGS. 8A and 8B, the lead 700includes a body 716 on which the fixation mechanism 710 is disposed. Asfurther shown, the fixation mechanism 710 includes a proximal floatingring 726 and a plurality of radially self-expanding ribs 736 attached atopposite ends to the ring 726 and to the body 716. A tendon 740 isdisposed within the body 716 (e.g., within a lumen, not shown) andattached to one or more locations on the ring 726. In the illustratedembodiment, a portion of the tendon 740 extends through an aperture 746in the body 716 and along the outer surface 720 to the ring 726 to whichit is attached. Other embodiments (not shown) may employ an alternativearrangement for attaching the tendon 740 to the ring 726.

A tensile force applied to the tendon 740 operates to pull the proximalring 726 in the proximal direction to retain the self-expanding ribs 736in the radially collapsed configuration of FIG. 7A for delivery of thelead 700. In one embodiment, the tendon 740 is secured, under tension,near the proximal end (not shown) of the lead 700. Once the lead 700 isdelivered to the desired implantation location, the tension in thetendon 740 is released, and the self-expanding ribs 736 expand to theirdeployed configuration as illustrated in FIG. 8B.

In the illustrated embodiments, the ribs 636, 736 are shown disposed onthe outside of the outer surface 620, 720 of the respective lead bodywhen in the radially collapsed, undeployed configuration. In anotherembodiment (not shown), the ribs may be substantially flush with therespective outer surfaces when in the radially collapsed configuration,for example, by residing in slots formed in the lead body. Additionally,in some embodiments, the ribs may be formed integrally with the leadbody. In other embodiments, the fixation mechanisms 610, 710 may beseparate elements, with the ribs attached to an anchor (not shown) whichis in turn attached to the lead body.

The ribs 636, 736 may, in some embodiments, be formed from any of thematerials described above in connection with the fixation mechanisms300, 400. In particular, in the self-expanding rib embodiments, the ribsare made at least partially from materials having desirable shape memoryand superelastic properties such as, for example, Nitinol. In otherembodiments, the ribs may be formed from the same materials used to formthe lead body (e.g., polyurethane and/or silicone).

In some embodiments, the ribs 636, 736 may be configured to facilitateextraction of the leads, if desired. For example, in one embodiment, theribs 636 and/or 736 may include a polymer membrane (not shown) made ofan ingrowth resistant material (e.g., PTFE) to prevent or substantiallyimpede tissue ingrowth in the space between the rib and the respectivelead. In other embodiments, the ribs 636, 736 themselves may be madefrom a material, such as PTFE, that is resistant to tissue ingrowth. Insome embodiments, the ribs 636, 736 may be made from resorbablematerials, as are known in the art, to facilitate extraction even afterextended periods of implantation.

FIGS. 9A and 9B illustrate a portion of a distal region of a lead 800including an alternative fixation feature, which as illustrated is aradially expandable fixation mechanism 810 according to anotherembodiment of the present invention. As shown in FIGS. 9A and 9B, thelead 800 includes a lead body 816 having an outer surface 820. Thefixation mechanism 810 is disposed on the lead body 616 and includes asheath 826 having a proximal portion 827, a distal portion 828, and afloating reinforcing ring 830 at a distal end 832. A tendon 840 isdisposed partially within the body 816 (e.g., within a lumen, not shown)and attached to one or more locations on the distal ring 830 insubstantially the same manner as described above in connection with, forexample, the leads 300, 500 and 600. The proximal portion 827 of thesheath 826 is frictionally coupled to the outer surface 820 of the leadbody 816. The reinforcing ring 830 is adapted to translate along thelead body 816.

In the illustrated embodiment, the sheath 826 is normally in theradially collapsed configuration as shown in FIG. 9A for delivery of thelead 800, and a tensile force is applied to the tendon 840 to pull thetendon 840 and the reinforcing ring 830 proximally relative to the leadbody 816 to deploy the fixation mechanism 810. The frictional forcescoupling the proximal portion 827 and the outer surface 820 prevent theproximal portion 827 from sliding proximally along the lead body 816under the action of the tensile force on the tendon 840. The distalportion 828 of the sheath 826 is sufficiently flexible, however, suchthat as the reinforcing ring 830 is pulled proximally under the actionof the tensile force on the tendon 840, the distal portion 828 will tendto bunch up and expand radially outward as shown in FIG. 9B to form atissue engaging surface for lead fixation.

As with various embodiments described above, the tendon 840 may, in oneembodiment, be secured to the lead body 816 under tension to maintainthe sheath distal portion 828 in its deployed configuration shown inFIG. 9B. In other embodiments, the lead 800 may include structures, suchas the retention structures described above, to prevent movement of thereinforcing ring 830 in the distal direction once the fixation mechanism810 is deployed. As with the embodiments described above, any otherstructures or methods for retaining the fixation mechanism 810 in thedeployed configuration of FIG. 9B may be used.

The sheath 826 may have any structure providing the desired flexibility.In one embodiment, the sheath 826 may be a braided tube which may or maynot include a polymeric coating. In one embodiment, the sheath 826 maybe a reinforced or an unreinforced polymer tube. In some embodiments,the sheath 826 may include a coating or layer of material thatdiscourages or substantially prevents tissue ingrowth (e.g., PTFE).

The tendons of the various embodiments can have any structure capable ofreceiving and transmitting a static tensile load while providing thedesired flexibility, and in the embodiments where the tendon ismaintained under tension, having desired fatigue responsecharacteristics. For example, the tendon may be in the form of a wire,cable, or thread. Suitable tendon materials include, without limitation,suture materials as are known in the art as well as other polymers andmetals such as stainless steel or superelastic alloys such as Nitinol.The tendon may optionally be coated with a lubricious material to reducefrictional forces between the tendon and the inner wall of therespective lumen carrying the tendon.

Any or all of the fixation features described above may includeadditional features to enhance frictional engagement for acute and/orchronic fixation, as desired. By way of example only, such featuresinclude, surface roughening or other surface treatments to increasefrictional engagement with the cardiac vessel tissue. Additionally, insome embodiments in which removability is desired, the fixation featuresmay include polymer coatings or other features to discourage tissueingrowth and facilitate removal and/or repositioning of the lead ifdesired.

It is emphasized that in some embodiments, the radially expandablefixation mechanisms do not extend completely circumferentially aroundthe respective lead bodies. Additionally, the floating members (e.g.,the ring 330 of the fixation mechanism 310) can have any structureadapted to permit translation along the lead body. For example, thefloating member could be configured to ride in a slot in the lead body,and need not be configured as a ring as shown in the illustratedembodiments.

Thus, to fixate a portion of a cardiac lead in a target cardiac vesselusing any of the deployable fixation features described above, the leadis first transvenously delivered to its implantation position with thefixation feature in its undeployed state. Such lead delivery can beaccomplished according to any method and using any delivery device nowknown (e.g., guide catheters, guide wires) or later developed. Once thelead is delivered, the tendon (or in some embodiments, a plurality oftendons) can be actuated to deploy the fixation feature(s) and securethe lead in its implanted position.

In the embodiments in which a tensile force applied to the tendon causesthe fixation feature to be deployed (e.g., the leads 50, 150, 250, 300,500, 600, 800 described above), the lead may be held in place as thetensile force is applied to the tendon, so as to prevent the lead itselffrom being displaced under the action of the tensile force. By way ofexample only, for the lead 300 described above, the proximal end of thelead can be held in place while the tensile force is applied to thetendon 340 to expand the radially expandable structure 336. Once thefixation feature is deployed in frictional engagement with therespective cardiac vessel wall, the tendon can be secured to the lead,if necessary, to retain the fixation feature in its deployedconfiguration. Alternatively, in embodiments including other structures(e.g., the retention structures 350 of the lead 300) to retain thefixation feature in its deployed configuration, the tension in thetendon can be relieved after deployment, or the tendon can be removedfrom the lead altogether if desired.

In other embodiments utilizing a self-expanding fixation feature that isretained in its undeployed configuration by tension in the tendon (e.g.,the leads 400, 700 above), the tension can be removed after the lead isdelivered to its implantation position as described above. Removal ofthis tension thus activates the fixation feature and causes the fixationfeature to frictionally engage the respective vessel wall. The tendoncan be left in place within the lead, or if desired, can be removed(e.g., by cutting the tendon).

FIGS. 10A and 10B are partial cross-sectional views of a portion of amulti-lumen lead 850 adapted to include the various fixation featuresillustrated and described above. As shown in FIGS. 10A and 10B, the lead850 includes a body 856 including an outer insulating sheath 858, and aconductor coil 860 covered by the insulating sheath 858 and defining aprimary lumen 866. As further shown, a secondary lumen 870 is disposedwithin the insulating sheath 858 for carrying a tendon 876 adapted foruse with any of the foregoing fixation features. Thus, in theillustrated embodiment, the tendon 876 for deploying the fixationfeature (not shown) is not carried by the primary lumen 866. It isemphasized that the multi-lumen lead 850 can be used with any of thedeployable fixation features illustrated herein and described above.Additionally, in some embodiments, more than one secondary lumen can beprovided to accommodate additional tendons or for other purposes (e.g.,drug delivery).

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

1. An implantable system comprising: a pulse generator; and a leadhaving a proximal end coupled to the pulse generator, the leadconfigured to be partially implanted in a cardiac vessel and including:an elongate lead body defining a proximal region and a distal region andincluding an outer insulating sheath, the distal region including anelectrode on the body, a deflection location on the body in which aportion of the outer insulating sheath has been removed to form thedeflection location, and a deflectable region having a tissue-engagingouter surface; and a tendon disposed at least partially within the bodyand attached to the body under tension at a first attachment locationdistal to the deflectable region, wherein the lead is configured suchthat tension in the tendon maintains the deflectable region in adeflected shape in which the tissue-engaging outer surface canfrictionally engage an inner wall of the cardiac vessel.
 2. The lead ofclaim 1 wherein the distal region includes a plurality of deflectionlocations on the lead body, and wherein the deflectable region isadapted to deflect at each of the deflection locations.
 3. The lead ofclaim 1 wherein the deflection location includes transition from arelatively stiff material to a relatively flexible material.
 4. The leadof claim 3 wherein the relatively stiff material is polyurethane and therelatively flexible material is silicone.
 5. The lead of claim 1 whereinthe deflection location includes a transition from a first portion ofthe lead body having a first wall thickness to a second portion of thelead body having a second wall thickness, wherein the first wallthickness is greater than the second wall thickness.
 6. The lead ofclaim 1 wherein the deflected shape is a J-shape.
 7. The lead of claim 1and further comprising a distal tip, wherein the first attachmentlocation is next to the distal tip.
 8. The lead of claim 1 furthercomprising a distal tip, wherein the first attachment location isproximal to the distal tip.
 9. The lead of claim 1 wherein the deflectedshape is an S-shape.
 10. The lead of claim 1 wherein the distal regionincludes a plurality of deflection locations, and wherein the deflectedshape is a sinusoidal shape.
 11. The lead of claim 1 wherein the distalregion includes a plurality of deflection locations offset from eachother about a circumference of the lead body, and wherein the deflectedshape includes a three-dimensional curve.